Glibc

Check glibc version

$ ldd --version
$ ldd --version
ldd (Ubuntu GLIBC 2.35-0ubuntu3) 2.35
Copyright (C) 2022 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Written by Roland McGrath and Ulrich Drepper.


or

$ strings /lib/x86_64-linux-gnu/libc.so.6 | grep -i GLIBC_
...
...
GLIBC_2.33
GLIBC_2.34
GLIBC_2.35
GLIBC_PRIVATE
...
...

Current glibc version support list

use the link to search
focal: 2.31
jammy: 2.35
...
...

modity the file: /etc/apt/sources.list

$ sudo apt update
$ sudo apt install libc6

install gcc

sudo apt-get install gcc-9 g++-9
$ sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-9 60 --slave /usr/bin/g++ g++ /usr/bin/g++-9
$ sudo update-alternatives --config gcc